[PATCH 5.10 401/406] net/tls: do not free tls_rec on async operation in bpf_exec_tx_verdict()

Greg Kroah-Hartman
2023-09-17T19:43:24Z

From: Liu Jian <liujian56@huawei.com>

[ Upstream commit cfaa80c91f6f99b9342b6557f0f0e1143e434066 ]

I got the below warning when do fuzzing test:
BUG: KASAN: null-ptr-deref in scatterwalk_copychunks+0x320/0x470
Read of size 4 at addr 0000000000000008 by task kworker/u8:1/9

CPU: 0 PID: 9 Comm: kworker/u8:1 Tainted: G OE
Hardware name: linux,dummy-virt (DT)
Workqueue: pencrypt_parallel padata_parallel_worker
Call trace:
dump_backtrace+0x0/0x420
show_stack+0x34/0x44
dump_stack+0x1d0/0x248
__kasan_report+0x138/0x140
kasan_report+0x44/0x6c
__asan_load4+0x94/0xd0
scatterwalk_copychunks+0x320/0x470
skcipher_next_slow+0x14c/0x290
skcipher_walk_next+0x2fc/0x480
skcipher_walk_first+0x9c/0x110
skcipher_walk_aead_common+0x380/0x440
skcipher_walk_aead_encrypt+0x54/0x70
ccm_encrypt+0x13c/0x4d0
crypto_aead_encrypt+0x7c/0xfc
pcrypt_aead_enc+0x28/0x84
padata_parallel_worker+0xd0/0x2dc
process_one_work+0x49c/0xbdc
worker_thread+0x124/0x880
kthread+0x210/0x260
ret_from_fork+0x10/0x18

This is because the value of rec_seq of tls_crypto_info configured by the
user program is too large, for example, 0xffffffffffffff. In addition, TLS
is asynchronously accelerated. When tls_do_encryption() returns
-EINPROGRESS and sk->sk_err is set to EBADMSG due to rec_seq overflow,
skmsg is released before the asynchronous encryption process ends. As a
result, the UAF problem occurs during the asynchronous processing of the
encryption module.

If the operation is asynchronous and the encryption module returns
EINPROGRESS, do not free the record information.

Fixes: 635d93981786 ("net/tls: free record only on encryption error")
Signed-off-by: Liu Jian <liujian56@huawei.com>
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Link: https://lore.kernel.org/r/20230909081434.2324940-1-liujian56@huawei.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/tls/tls_sw.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c
index ac7feadb43904..50eae668578a7 100644
--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -810,7 +810,7 @@ static int bpf_exec_tx_verdict(struct sk_msg *msg, struct sock *sk,
psock = sk_psock_get(sk);
if (!psock || !policy) {
err = tls_push_record(sk, flags, record_type);
- if (err && sk->sk_err == EBADMSG) {
+ if (err && err != -EINPROGRESS && sk->sk_err == EBADMSG) {
*copied -= sk_msg_free(sk, msg);
tls_free_open_rec(sk);
err = -sk->sk_err;
@@ -839,7 +839,7 @@ static int bpf_exec_tx_verdict(struct sk_msg *msg, struct sock *sk,
switch (psock->eval) {
case __SK_PASS:
err = tls_push_record(sk, flags, record_type);
- if (err && sk->sk_err == EBADMSG) {
+ if (err && err != -EINPROGRESS && sk->sk_err == EBADMSG) {
*copied -= sk_msg_free(sk, msg);
tls_free_open_rec(sk);
err = -sk->sk_err;
--
2.40.1